1. Field of the Invention
This invention relates to a charge forming device for piston type internal combustion engines designed to be supplied with fuel carried in an intake air stream.
2. Problem to be Solved and Discussion of Prior Art
The problem solved by the present invention is that of providing, in an internal combustion engine that receives a fuel and air charge through a charge intake port, substantially fuel-free air at the intake valve at the moment the intake valve is opened during an intake event while yet providing a total charge of fuel and air for each intake that meets the requirement of the power cycle of the engine. The initial fuel-free air is desired to enable proper distribution of air and fuel within the working chamber of the engine in a manner that will be evident from the description that follows.
Various prior art exists illustrating the use of valve arrangements for injecting auxiliary air into the intake manifold or port area of an internal combustion engine to provide auxiliary air intended to solve specific problems. U.S. Pat. No. 3,561,412 is an example of such prior art. However, the specific problem of providing fuel-free air to a cylinder at the beginning of an intake event by regulating the timed charge of the required fuel between intake events upstream of the intake port does not seem to have been considered in such prior art.